..What Actually Is HO?

[jim-bob]

..If HO on a new engine means high-output, that means more HP, right? How much more and what actually was done at the factory to make it HO..
Is there anything negative, besides money, on buying say a 350HO versing just a 350?
And couldn't you increase a new "standard" 350 eng. by getting a carb with higher cfm and installing long tube headers, etc?

Thanks!

[dubds10]

HO is high output, but every engine is different in the sense of what has been done to it to make it HO vs a regular engine. That's going to be VERY broad and you can't really get just one simple answer as to what makes an engine HO, besides anything above stock could be considered HO lol Obviously when it comes to classic engines and rare engines from the muscle car era there are known differences but those you do your research on to make sure of course.

If you're looking at crate motor, you'll just have to read the specs to figure out what the differences are between the various engines that make one a HO engine vs a regular 350. There's no disadvantage to more power

Nate

[jocko]

HO usually means more hp than the base model that the place offers. GM offers some HO designated motors that have upgrades in component performance levels as well as "longevity" assuming it's gonna be pounded on. Cast vs Hypereutectiv vs forged pistons, roller vs flat tappet cams, induction system/cfm, etc. HO for GM usually means vortech heads at a minimum, but hp/torque levels of their different offerings usually increases directly proportionally to price.

To your last question - yes, you could build it yourself, but then you miss out on the engineering that the factory has put into its proven combos. If you WANT more hp, etc, then a HO crate is a good option. If you want to build old school - might not get the same bang for the buck (both hp and reliability) doing it yourself. My 2 cents.
Having sad that, I prefer the non-crate route and building what I've wanted in the past - so it certainly comes down to pers pref.

[cdowns]

buying a new crate enginee and changing it out for higher horspower voids a great warrenty// to me that is the number one selling point of a GM engine in a box

[prostreetC-10]

It's also the first of 3 sounds that Santa makes just before he slides down your chimney!!

[prostreetC-10]

"And couldn't you increase a new "standard" 350 eng. by getting a carb with higher cfm and installing long tube headers, etc?"



FWIW.....increasing a carbs CFM rating will do nothing but hurt performance and gas mileage if what is already on it is ideal. Carbs don't supply power.....they supply fuel so the motor can make power. They are not like NOS or BOOST where the more you give the more power you make. You want exactly what the motor can use and no more.

[jim-bob]

Originally Posted by prostreetC-10

"And couldn't you increase a new "standard" 350 eng. by getting a carb with higher cfm and installing long tube headers, etc?"



FWIW.....increasing a carbs CFM rating will do nothing but hurt performance and gas mileage if what is already on it is ideal. Carbs don't supply power.....they supply fuel so the motor can make power. They are not like NOS or BOOST where the more you give the more power you make. You want exactly what the motor can use and no more.

Ok, I'm set to buy a new GM 350HO crate engine which doesn't come with carb and it has been suggested to buy a Holley 750CFM for it..what's yall thinking?
And just for my knowledge, what does the carb's different CFM's do for the engine? Why would buy, say, a 650cfm or 750cfm etc?
Thanks!

[prostreetC-10]

750 seems like a lot for "today's" 350HOs...but I don't know a thing about the motor. Most 350s rip with a 650/670 carb. 600s fit many builds too. Tell us more about the motor. HP rating....cam....intended RPM...those things.

[Stocker]

It's been said, but... everything needs to be designed to work together.

As to carbs, my knowledge is very limited, but I can tell you this. I once owned a '65 Corvette with a 327/365. It was the strongest carbureted factory SBC of its time, and identical to the 375HP injected engine but for the induction system. Redline was 6500 rpm and easily achieved in top gear. Didn't idle too well but it pulled like crazy... very strong. To the best of my recollection, its single-inlet Holley was rated at 600 CFM (possibly 650, but no more).

This is just to show that you won't gain anything by bolting on a carb that's bigger than the engine needs....